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From: John Darrington <john@darrington.wattle.id.au>
To: Jeff Law <law@redhat.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>,
	       Paul Koning <paulkoning@comcast.net>,
	       Vladimir Makarov <vmakarov@redhat.com>,
	       John Darrington <john@darrington.wattle.id.au>,
	gcc@gcc.gnu.org
Subject: Re: Indirect memory addresses vs. lra
Date: Fri, 09 Aug 2019 08:14:00 -0000	[thread overview]
Message-ID: <20190809081439.baoyu3ii5i2qfbzt@jocasta.intra> (raw)
In-Reply-To: <dca38a3f-91db-9483-dd0e-0075ef501624@redhat.com>

On Thu, Aug 08, 2019 at 01:57:41PM -0600, Jeff Law wrote:

     Yea, it's certainly designed with the more mainstream architectures in
     mind.  THe double-indirect case that's being talked about here is well
     out of the mainstream and not a feature of anything LRA has targetted to
     date.  So I'm not surprised it's not working.
     
     My suggestion would be to ignore the double-indirect aspect of the
     architecture right now, get the port working, then come back and try to
     make double-indirect addressing modes work.
     
This sounds like sensible advice.  However I wonder if this issue is
related to the other major outstanding problem I have, viz: the large 
number of test failures which report "Unable to find a register to
spill" - So far, nobody has been able to explain how to solve that
issue and even the people who appear to be more knowlegeable have
expressed suprise that it is even happening at all.

Even if it should turn out not to be related, the message I've been
receiving in this thread is lra should not be expected to work for
non "mainstream" backends.  So perhaps there is another, yet to be
discovered, restriction which prevents my backend from ever working?

On the other hand, given my lack of experience with gcc,  it could be
that lra is working perfectly, and I have simply done something
incorrectly.    But the uncertainty voiced in this thread means that it
is hard to be sure that I'm not trying to do something which is
currently unsupported.

J'

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  reply	other threads:[~2019-08-09  8:14 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-04 19:18 John Darrington
2019-08-08 16:25 ` Vladimir Makarov
2019-08-08 16:44   ` Paul Koning
2019-08-08 17:21     ` Segher Boessenkool
2019-08-08 17:25       ` Paul Koning
2019-08-08 19:09         ` Segher Boessenkool
2019-08-08 17:30       ` Paul Koning
2019-08-08 19:19         ` Segher Boessenkool
2019-08-08 19:57           ` Jeff Law
2019-08-09  8:14             ` John Darrington [this message]
2019-08-09 14:17               ` Segher Boessenkool
2019-08-09 14:23                 ` Paul Koning
2019-08-10  6:10                 ` John Darrington
2019-08-10 16:15                   ` Segher Boessenkool
2019-08-09 16:07               ` Jeff Law
2019-08-09 17:34               ` Vladimir Makarov
2019-08-10  6:06                 ` John Darrington
2019-08-10 16:12                   ` Segher Boessenkool
2019-08-12  6:47                     ` John Darrington
2019-08-12  8:40                       ` Segher Boessenkool
2019-08-12 13:35                   ` Vladimir Makarov
2019-08-15 16:29                   ` Vladimir Makarov
2019-08-15 16:38                     ` Richard Biener
2019-08-15 17:41                       ` John Darrington
2019-08-15 18:30                       ` Vladimir Makarov
2019-08-15 21:22                         ` Segher Boessenkool
2019-08-15 17:36                     ` John Darrington
2019-08-15 18:23                       ` Vladimir Makarov
2019-08-16 11:24                         ` Special Memory Constraint [was Re: Indirect memory addresses vs. lra] John Darrington
2019-08-16 14:50                           ` Vladimir Makarov
2019-08-19  7:36                             ` John Darrington
2019-08-19 13:14                               ` Vladimir Makarov
2019-08-19 15:07                                 ` Segher Boessenkool
2019-08-19 18:06                                   ` John Darrington
2019-08-20  6:56                                     ` Richard Biener
2019-08-20  7:07                                       ` John Darrington
2019-08-20  7:30                                         ` Richard Biener
2019-08-08 18:46     ` Indirect memory addresses vs. lra Vladimir Makarov

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